There are many systems for removing molten slag from wet bottom boilers. Most of these systems utilize horizontal tap holes (parallel to the boiler floors). Molten slag flows through these tap holes and into water filled tanks, which by the chilling effect of cool water causes the molten slag to solidify and disintegrate into a course granular product. The resultant black slag particles are discharged hydraulically at regular intervals from the slag tanks.
However, due to the load changes, combustion conditions or the type of coal the boiler is fueled with, the molten slag sometimes tends to thicken and become "gummy" causing the tap holes to close. This creates a most serious problem and many man-hours of labor are presently spent in reopening closed horizontal tap holes to insure maintaining a boiler in service.
Examples of various forms of slag removal systems previously known are disclosed in the following U.S. patents:
U.S. Pat. Nos. 545,001--Aug. 20, 1895--VanCleve et al.; 2,149,688--Mar. 7, 1939--Schott; 2,548,656--Apr. 10, 1951--Dolezal; 2,667,848--Feb. 2, 1954--Silk; 3,133,804--May 19, 1964--Hardgrove; 3,395,995--Aug. 6, 1968--Burch; 3,741,136--June 26, 1973--Stookey.